Raycast Shooting [Need help]

Hello! I am new to unity and C# i am trying to make my gun shoot with recoil. I think i got it to work. But some times when i shoot in the wall i don't get a bullet hole. Same with the ground.

Heres my code:

 using UnityEngine;
 using System.Collections;
 
 public class PM_40 : MonoBehaviour {
     public GameObject texture;
     GameObject Gun;
     GameObject Receiver;
     float rateFire = 0.4f;
     float countDown;
     float speed = 10;
     bool canShot = true;
     bool gunCocking = false;
     public AudioClip pistolSound;
     public AudioClip pistolReloadSound;
     public AudioClip pistolCokingSound;
     float ammo = 12;
     float recoil = 0.1f;
     Vector3 randomHit;
 
 
 
 
 
     // Use this for initialization
     void Start () {
         Gun = GameObject.Find("PM_40");
         Receiver = GameObject.Find("PM-40_Top");
 
 
     }
     
     // Update is called once per frame
     void Update () {
        
 
         if (ammo == 0)
         {
             gunCocking = true;
             if (Input.GetKeyDown("r"))
             {
                 Camera.main.GetComponent<AudioSource>().clip = pistolReloadSound;
                 Camera.main.GetComponent<AudioSource>().Play();
                 gunCocking = false;
                 ammo = 12;
                
             }
 
             if (Input.GetMouseButtonDown(0) && gunCocking == true)
             {
 
                 Camera.main.GetComponent<AudioSource>().clip = pistolCokingSound;
                 Camera.main.GetComponent<AudioSource>().Play();
             }
 
 
         } else
         {
             gunCocking = false;
         }
      
        
 
 
 
         if (canShot == false)
         {
            
             if (countDown > 0)
             {
                 countDown -= Time.deltaTime;
             }
 
 
             if(countDown < 0)
             {
                 countDown = 0;
                 canShot = true;
             }
           
 
         }
        
 
         Ray ray = Camera.main.ScreenPointToRay(new Vector3(Screen.width / 2, Screen.height / 2));
         Debug.DrawRay(ray.origin, ray.direction * 10000, Color.yellow);
         RaycastHit hit;
 
        
             
             if(Input.GetMouseButtonDown(0) && canShot == true && ammo > 0){
 
                 transform.Rotate(0, recoil * Time.deltaTime, 0);
                 Camera.main.GetComponent<AudioSource>().clip = pistolSound;
                 Camera.main.GetComponent<AudioSource>().Play();
 
                 
                 Gun.transform.position = new Vector3(Gun.transform.position.x, Gun.transform.position.y, Gun.transform.position.z - recoil);
 
 
             if (Physics.Raycast(ray, out hit))
             {
                 if (Input.GetMouseButton(1))
                 {
                     randomHit = new Vector3(hit.point.x + Random.Range(-0.01f, 0.01f), hit.point.y + Random.Range(-0.01f, 0.01f), hit.point.z);
                 }
                 else
                 {
                     randomHit = new Vector3(hit.point.x + Random.Range(-0.4f, 0.4f), hit.point.y + Random.Range(-0.4f, 0.4f), hit.point.z);
                 }
 
 
               
                 Instantiate(texture, randomHit, Quaternion.LookRotation(Vector3.up, hit.normal));
             }
 
             ammo--;
             countDown = rateFire;
                
                 canShot = false;
 
             }
           
      
 
 
         
 
 
 
     }
 
 
 
     void OnGUI()
     {
 
         GUI.Box(new Rect(Screen.width - 100, Screen.height - 30, 100, 25), "Ammo: " + ammo);
     }
 
 
 
 }